another common place i have seem people miss is the Idle screw o ring. remove your idle screw and replace the o ring with any o ring of that size than go from there
when you have to turn the idle screw all the way in. you have a air leak somewhere. check and make sure the Idle Air Control Valve is working properly.
when my 3.0 V6 wouldnt idle at the correct engine speed. it ended up being my IACV which i disabled
